This will require:
- A PSP
- A USB cable
- A Memory Stick
First off, get a PS1 gamesave in the PS1 format (the ones meant for POPStation). If you have a save thats not in the PSP format Im pretty positive there are converters.
Place your savegame in ms0:/PSP/SAVEDATA.
Hook your PSP up to your PS3 via USB.
In the XMB, click [Memory Card Utility (PS/PS2)].
Then click on [PSP].
It should give you a list of the PS1 saves on your PSP's mem stick. Then simply copy then to your HDD.